LIST OF CARABIDAE COLLECTED ON BIOKO, SEPT.-OCT., 1998
DISCUSSION OF TARGET TAXA CARABID BEETLES (INSECTA: COLEOPTERA; CARABIDAE) COLLECTED IN BIOKO, EQUATORIAL GUINEA, SEPTEMBER-OCTOBER, 1998
Report of Preliminary Findings by David H. Kavanaugh Curator of Entomology, California Academy of Sciences
Collections made during the Academy’s expedition to Bioko, Equatorial Guinea, in September-October 1998, included 98 beetle specimens belonging to the Family Carabidae. This material has been preliminarily sorted to morphospecies and initial study suggests that a total of 28 species are represented. No comprehensive study of the carabid fauna of west Africa in general or of Bioko in particular has been published or even undertaken, and the literature to date for the fauna of the region includes only isolated descriptions of species. It is therefore not possible to accurately identify any of the material collected to species or, except in a few instances, even to genus except by comparison with type material, all of which is deposited in collections in Europe (mainly in Paris). I will not be able to make the necessary comparisons until at least a year from now, so the attached list represents the best determinations that can be made at present. However, even without more detailed identifications, it is possible to make certain generalizations about the carabid fauna of Bioko from the initial sampling effort. Fully half of the species in the collections made are represented by single specimens only. This suggests that the carabid fauna of Bioko was only partially sampled, that many additional species will be found to occur there, and that the carabid fauna is certainly richer, more diverse, than is presently known. An overview of the carabids collected suggests a fauna with a distinctly Pantropical appearance, with groups common to Africa, southeast Asia, the Indo-Australian region, and even South America represented. From a cursory review of the extensive holdings of African carabids in the Academy’s collections, most of which, unfortunately, remain unidentified at present, it is clear that the carabids of Bioko have closest affinities with the fauna of the adjacent mainland of Africa, especially with the fauna of Cameroon. It is not yet possible to determine what percentage of the species sampled are in fact common to both Bioko and the mainland, but it is likely that a majority of species in the Bioko fauna will fall in this category. Several of the carabids examined are short-winged, flightless forms, and all of these were collected in montane habitats on Pico Basilé. Typically, and on a worldwide basis, flightless, montane carabid beetles occupy highly restricted geographical ranges, often being confined to single peaks or mountain ranges, with most closely related species found on adjacent peaks or ranges. It is therefore likely that at least three, and probably more, of the species sampled are endemic to the island of Bioko, more specifically to higher, undisturbed montane habitats on Pico Basilé, and will be found nowhere else. Certainly, the survival of such unique, endemic forms is a serious conservation concern. Different but related species most probably occupy montane habitats on the mainland, particularly in the highlands of Cameroon.